"The idea that we are the only intelligent creatures in a cosmos
of a hundred billion galaxies is so preposterous that there are very
few astronomers today who would take it seriously. It is safest to
assume therefore, that they are out there and to consider the manner in
which this may impinge upon human society."

Arthur C. Clarke, physicist and author of 2001: A Space Odyssey

The world-renowned physicist Lee Smolin author of Life of the Cosmos
says that what we should look for to confirm the existence of
intelligent life in the Milky Way is a message left for us some time in
the last several hundred million years.

Smolin suggests that one such
message might have been left in the genetic code of some living
creature in the language of nucleic acid bases in the DNA, confident
that the ability of living creatures to replicate DNA would keep the
message relatively uncontaminated for the time scales of this order.
There is a great deal of DNA in most species that does not play any
biological role and varies enormously from species to species without
apparent cause. The existence of this DNA is one of the puzzles of
molecular biology.

The unsolved question of the existence of
extraterrestrial intelligence is one of the greatest scientific challenges that currently
confronts humanity.

The Fermi paradox is the apparent contradiction between high
estimates of the probability of the existence of extraterrestrial
civilizations and the lack of evidence for or contact with such
civilizations.

The 14-billion-year age of the universe and its
130 billion galaxies and a Milky Way Galaxy with some 400 billion stars
suggest that if rocky planets like Earth orbiting around small yellow stars are typical, intelligent life should be
common. Using NASA's Spitzer Space Telescope, a team of scientists found that
at least 20 percent, and possibly the majority (as many as 60 percent)
of stars similar to the sun are candidates for forming rocky planets.
The Legacy Science Program set out to determine whether planetary
systems like ours are common or rare in the Milky Way. What they found
is that many, perhaps even most, of the sun-like stars in our galaxy
could well harbor Earth-like planets.

The ideal stars to support planets suitable for life for tens of billions of years may be a smaller slower burning ‘orange dwarf’ with a longer lifetime than the Sun ― about 20-40 billion years. These stars, called K stars, are stable stars with a habitable zone that remains in the same place for tens of billions of years. They are 10 times more numerous than Sun G-class stars, and may provide the best potential habitat for life in the long run.

Nobel laureate Enrico Fermi, discussing this observation with
colleagues over lunch in 1950, asked, logically: "Where are they?" Why,
if advanced extraterrestrial civilizations exist in our Milky Way
galaxy, hasn't evidence such as probes, spacecraft, or radio
transmissions been found?

As our technologies become ever more sophisticated and the search
for extraterrestrial intelligence continues to fail, the "Great
Silence" becomes louder than ever. The seemingly empty cosmos is
screaming out to us that something is amiss. Or is it?

Using a computer simulation of our own galaxy, the Milky Way,
Rasmus Bjork, a physicist at the Niels Bohr Institute in Copenhagen,
proposed an answer to the Fermi Paradox. Bjork proposed that an alien civilization might
build intergalactic probes and launch them on missions to search for
life.

He found, however, that even if the alien ships could hurtle through
space at a tenth of the speed of light, or 30,000km a second, - NASA's
current Cassini mission to Saturn is gliding along at 32km a second -
it would take 10 billion years, roughly half the age of the universe, to
explore a mere four percent of the galaxy.

Like humans, alien civilizations could shorten the time to find
extra-terrestrials by picking up television and radio broadcasts that
might leak from colonized planets. "Even then," he reported in the New
Scientist, "unless they can develop an exotic form of transport that
gets them across the galaxy in two weeks it's still going to take
millions of years to find us. There are so many stars in the galaxy
that probably life could exist elsewhere, but will we ever get in
contact with them? Not in our lifetime."

The problem of distance is compounded by the fact that timescales
that provide a "window of opportunity" for detection or contact might
be quite small. Advanced civilizations may periodically arise and fall
throughout our galaxy as they do here, on Earth, but this may be such a
rare event, relatively speaking, that the odds of two or more such
civilizations existing at the same time are low.

In short, there may have been intelligent civilizations in the
galaxy before the emergence of intelligence on Earth, and there may be
intelligent civilizations after its extinction, but it is possible that
human beings are the only intelligent civilization in existence "now."
"Now" assumes that an extraterrestrial intelligence is not able to
travel to our vicinity at faster-than-light speeds, in order to detect
an intelligence 1,000 light-years distant, that intelligence will need
to have been active 1,000 years ago.

There is also a possibility
that archaeological evidence of past civilizations may be detected
through deep space observations — especially if they left behind large
artifacts such as Dyson spheres.

Perhaps...but in
our search for life and intelligence we have to keep in mind that the
Milky Way Galaxy is two or three times the age of our Solar System, so
there are going to be
some societies out there that are millions of years, maybe more, beyond
ours, which may have proceeded beyond biology—that have invented
intelligent, self-replicating machines and it could be that what we
first find is something
that's artificially constructed if we have the ability to recognize it
as such. It may very well be that our greatest discovery will be that
the very nature of alien communication will prevent our being able to
communicate with it.

Comments

who said that the current common human concepts are intelligent? if i were a smart extraterrestrian, i certainly would not want to deal with such a stupid, messy, vulgar and selfish species. what if higher intelligences are always with us and we are just too dumb to notice? how can we expect to connect to the rest of universe, when we seem to have serious trouble to connect to ourselves?

This was a cool article and you guys post such ridiculous comments on it. Leave humanity alone unless you are contributing to its betterment in an epically profound way. Any intelligent species who wouldn't want to make contact with another one ISN'T intelligent at all. And that includes people. And ants too, since you feel bringing up ants is relevant.

DNA could be governed by the laws of the universe, developing along lines defined by the same rules that govern the rest of existence, making its occurrence common or at least commonly attempted. While it is not the only possibility, "junk" DNA could be code that would only be activated under a different nurture system, or environmental evolutionary circumstances. Is DNA a relatively static development having its fate precluded by the very rules that allow its creation, thus making our unused DNA optional code for different upbringings? Or is it perhaps highly dynamic, having a design dynamically susceptible to the variations of the environment in which it resides, making such unused or unknown code something developed only during our path type to be deactivated as seen fit?

I have to agree with Robert and Dennis that we may want to raise the bar of "intelligence" to something more than our current capacity, though relativity does put us on the top of our own list as it's the best we've been able to do thus far. There's plenty of room for improvement with this point of view, Chris. In fact, self-critical thought is generally required outside the realm of luck and/or persistence for progress, even if it seems pessimistic. Optimism without critical thought tends to provide only an illusion of progress, such as blissful ignorance.

We think our universe is only ~500 times as old as the average life of an average star (calling the orange dwarf an average star)? I would be more inclined to believe this universe flexes - expands and contracts - on a regular basis, and we're surround by as many "universes" as we have galaxies near other galaxies, interacting with each other in an even greater ballet. Such flexing may orphan some of the outermost debris (yes, I’m referring to galaxies as debris). That debris will confound us if we assume our universe’s last compression was its beginning.

Maybe "intelligent" life forms roaming this galaxy have found so much life they haven't had time to get to us yet. Our radio signals have travelled how far? Less than 100 light years I assume. That isn't very far compared to the size of the galaxy we are in is it?

I think that the reason we don't see anyone is that "death by internet" is common. Higher and higher speed data tends not to leak very far and still be readable at a distance. Civilizations tend to fall inward into their own advanced computer networks. Once you can simulate any paradise you can imagine at incredible speeds, the physical universe outside will tend to look slow, difficult, and irrelevant. I think the relevant question should be "what will a very advanced computer network look like from a distance?" and "how long will an advanced computer network civilization last?"

While it is silly to bluntly say that humans are stupid, therefore aliens don't want to talk to us, it is a fact that we are an inherently warlike species, one of two on earth (the other ones being chimpanzees). Warlike behavior played a pivotal role in the development of civilization by nucleating tribes. This is of course, the only known way of starting civilizations in intelligent species, but it's not unreasonable to assume that other species have developed civilization without the need for warlike behavior. Under this assumption, it is reasonable that peaceful civilizations would be wary of contacting warlike civilizations for obvious reasons. However, if FTL travel is impossible, then this solution to the fermi paradox is reasonable.

We haven't found them because they are either avoiding us entirely or have found us first and don't want us to know. When you stop thinking inwardly about it, the idea becomes incredibly obvious. Especially given the notion that chances are extremely high that they are far more advanced than we can even comprehend due to the age of our solar system is far younger than the rest of the galaxy. Remember: those who deny the most they need to grow up are those who are in need of doing so the most.

I think our biggest error is thinking of life as carbon based. Extremophiles have thought us that even on earth what we define as 'living' is often challenged. Even the earth for example, it has a beginning, end, it moves, it breaths and has energy too, why don't we see it as a lifeform of it's own?

My first guess is that most of the civilizations out there have no desire to contact any other intelligent species, for reasons that will eventually become clear to us.

Nevertheless, I still think we will visit other star systems. I suspect we will find many other universes, a lot of them, which are adjacent to our own universe and into which we can somehow pass.

We will be able to look for a few nearby universes in which there are inhabited star systems near our entry point. The search may take a very long time, but at that point it will be easy (well, easier) to visit some of our meta-neighbors. They will be close at hand, but not lie within our original, limited space-time realm.

1) We only recently (within the last 60 years) were able to fully send a radio signal into space. (The German Olympics in 1936)
2) Scientists assume that life outside of Earth, if intelligent, would develop along the same path as we did.
3) It is quite possible that intelligent life is more than 70 light years away and therefor has not received an Earth originated signal, nor had the chance to have an incoming signal reach Earth yet.
4) We have proven time and time again that technology can develop along different paths, we just do not fully realize this as we did not attempt to go down a different path.

These debates usually resolve around the size of the universe. Most astronomers I've spoken to agree that the primary issue isn't space but time. There's excellent reason to believe that humanity as we know it could die out after a few thousand years of critical thought. That's a blink in the peripheral vision of the universe.

It's quite likely that there has been and will be lots of other life, but we're just alive at the wrong time to communicate with it.

I think they are waching us. They have the tecnology to know EVERTHING about us. You can see at our own movies (Knowing, The day the earth stood still, Transformers, ect) (Mars Attack, just kidding haha), they aren't so far from the truth. Do you have proof that Megatron (an example of a metalurgic-base civization) doesn't exist? Guys, ANYTHING is possible, if we are here, they could be there.

There has been evidence of flying saucer and disc flying all over earth. Pilots usually have stories, almost everybody has there own story about an encounter with aliens. Maybe they do exist... Maybe they have a reason not to let us know there there...

What curious beings we are. We cant live with the thought of being all alone in this universe, an idea that in my opinion is depressing. I just hope when we do make contact with another species, our world leaders will tell us. Its even more depressing to think that they would have the ability to keep the wool over our eyes. The thought that we are not alone is an inspiring one. It just further posses my belief that we are all apart of something bigger than ourselves, and however small the impact we can make as indivuals, it is still our impact. Only the indivual can make the impact they choose to create. And even though the feeling is minuet, it is still felt throughout the universe.

The universe may simply be so vast that we simply cannot contact other intelligent civilizations. Even if there are millions of space faring cultures out there, that doesn't mean one is close in proximity. The arrogance of humans is another crutch. Just because many intelligent societies may exist, it doesn't mean some of them have discovered (or ever will discover) a way to zip across the cosmos, or relay messages quickly around universe.

Slow and plodding space travel and messaging (slower than light or light speed) may actually be the norm for even the most advanced civilizations out there. Which would mean only the very close, and very ancient civilisation's messages would be reaching us by now. That likely narrows, or eliminates, the likelyhood of coming in contact with other intelligent worlds anytime soon.

What if life is everywhere out there, but we are the most advanced? So many questions. So many possibilities.

THE RIGHT COMMUNICATION METHOD?
Some people says that humans have been in contact with a variety of intelligent beings for thousands of years - but the modern human being have forgotten the necessary spiritual/intuitive capability of universal communication.

I also agree very much with you - though I´ve had much use of the measuring results of the modern science-

And I´ve used discoveries of Astronomy, Cosmology and even Astrophysics (and my own spiritual visions) in order to confirm the ideas of Ancient Mythological Knowledge, where all knowledge once was gathered in just 1 Big Story.